Open AccessThe H i content of star‐forming galaxies at z = 0.24
Author(s) -
Lah Philip,
Chengalur Jayaram N.,
Briggs Frank H.,
Colless Matthew,
De Propris Roberto,
Pracy Michael B.,
De Blok W. J. G.,
Fujita Shinobu S.,
Ajiki Masaru,
Shioya Yasuhiro,
Nagao Tohru,
Murayama Takashi,
Taniguchi Yoshiaki,
Yagi Masafumi,
Okamura Sadanori
Publication year - 2007
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2007.11540.x
Subject(s) - physics , astrophysics , giant metrewave radio telescope , galaxy , luminous infrared galaxy , star formation , redshift , radio galaxy , astronomy , elliptical galaxy , luminosity , content (measure theory) , mathematical analysis , mathematics
We use observations from the Giant Metrewave Radio Telescope (GMRT) to measure the atomic hydrogen gas content of star‐forming galaxies at z = 0.24 (i.e. a look‐back time of ∼3 Gyr). The sample of galaxies studied were selected from Hα‐emitting field galaxies detected in a narrow‐band imaging survey with the Subaru Telescope. The Anglo‐Australian Telescope was used to obtain precise optical redshifts for these galaxies. We then co‐added the H i 21‐cm emission signal for all the galaxies within the GMRT spectral line data cube. From the co‐added signal of 121 galaxies, we measure an average atomic hydrogen gas mass of (2.26 ± 0.90) × 10 9 M ⊙ . We translate this H i signal into a cosmic density of neutral gas at z = 0.24 of Ω gas = (0.91 ± 0.42) × 10 −3 . This is the current highest redshift at which Ω gas has been constrained from 21‐cm emission and our value is consistent with that estimated from damped Lyα systems around this redshift. We also find that the correlations between the Hα luminosity and the radio continuum luminosity and between the star formation rate (SFR) and the H i gas content in star‐forming galaxies at z = 0.24 are consistent with the correlations found at z = 0 . These two results suggest that the star formation mechanisms in field galaxies ∼3 Gyr ago were not substantially different from the present, even though the SFR is three times higher.